1. Field of the Invention
The present invention relates to a rotary electric shaver in which a plurality of cutter units including inner cutters rotating in sliding contact with the lower faces of outer cutters are provided on a shaver main body that houses a motor, etc.
2. Description of the Related Art
In one type of electric shaver, a plurality of outer cutters are provided in an outer cutter frame, which is securely attached to a shaver main body, so that the outer cutters are respectively allowed to make fine vertical (depressible) or pivotal motion (hereinafter simply and collectively called “vertical motion” as well) independently. In such shavers, the range of mobility of the outer cutters is generally small, and thus the shaving surfaces of the outer cutters cannot be brought close enough to the skin and is limited in possible improvements in shaving feeling.
The inventor of the present application has previously proposed an idea in which outer cutters are provided in respective substantially cage-like pivoting cases so as to make fine vertical motion and, on the other hand, these pivoting cases are disposed respectively in an outer cutter frame (that is securely attached to the shaver main body) so as to make independent pivotal motion (see FIG. 4, etc. of the Japanese Patent Application No. 2004-351628 (Laid-Open No. 2006-158519)).
In the electric shaver disclosed in the Japanese Patent Application National Publication (Kohyo) No. H9-503424, the outer cutters are respectively provided in a skin-supporting rim that is split into sections for each respective outer cutter, and adjacent skin-supporting rims are joined together with hinges or pivotally supported in a skin-supporting rim holder (which corresponds to the outer cutter frame securely attached to the shaver main body of the shaver of the invention of the present application).
In the shavers disclosed in the above-identified Japanese publications, the drive shafts (inner cutter drive shafts) that respectively correspond to the outer cutters are protruded from the shaver main body, and the upper ends of these drive shafts are engaged with the inner cutters through universal joints to rotate the inner cutters.
As seen from the above, in any of these conventional shavers, drive shafts corresponding to outer cutters are protruded from the shaver main body, and the upper ends of these drive shafts are engaged with the inner cutters of the cutter units through universal joints.
In such shavers, if the amount of pivotal motion of the outer cutters is small, then the range of flexion and extension/contraction of the universal joint is also small and, therefore, the load applied to the universal joint does not become excessively large. However, when the pivoting cases that hold the outer cutters (in Japanese Patent Application No. 2004-351628 (Laid-Open No. 2006-158519)) and the skin-supporting rims (in Japanese Patent Application National Publication (Kohyo) No. H9-503424) are rendered moveable separately from the outer cutters, the range of flexion and extension/contraction of the universal joints of the drive shafts increase. This leads to a decrease in the durability of the universal joints and contributes to the production of abnormal sounds and noise.